Math & Science ⇒ align command

[abu aasiyah]

Hey,

The align-command is such that when you type in several equation one on top of the other, every equation gets a number attached to it. How do you only attach a number to the last equation in the alignment. For instance:

Code: Select all

\documentclass[12pt,a4paper,danish]{article} 
\usepackage[latin1]{inputenc} 
\usepackage[danish]{babel} % danske overskrifter
\usepackage[T1]{fontenc} 
\usepackage{lmodern} 
\usepackage{graphicx} 
\usepackage{mathtools}
\usepackage{amsmath}

\begin{document}

\begin{align}
\frac{d^{2} \left( EI\frac{d^{2}\omega}{dx^{2}} \right)}  {dx^{2}}=p \quad& \Leftrightarrow \\
EI\frac{d^{2}  \left( \frac{d^{2}\omega}{dx^{2}} \right)} {dx^{2}}=p \quad& \Leftrightarrow \\
\frac{d^{4}\omega}{dx^{4}}=\frac{p}{EI}
\end{align}

\end{document}

[Stefan Kottwitz]

Hi,

use \notag for the lines where you don't want to give a number:

Code: Select all

\begin{align}
\frac{d^{2} \left( EI\frac{d^{2}\omega}{dx^{2}} \right)} {dx^{2}}=p \quad& \Leftrightarrow \notag\\
EI\frac{d^{2} \left( \frac{d^{2}\omega}{dx^{2}} \right)} {dx^{2}}=p \quad& \Leftrightarrow \notag\\
\frac{d^{4}\omega}{dx^{4}}=\frac{p}{EI}
\end{align}

Stefan

[frabjous]

If you want just one tag associated with the entire aligned sequence, another option would be to use the aligned environment inside an equation environment:

Code: Select all

\documentclass[12pt,a4paper,danish]{article}
\usepackage[latin1]{inputenc}
\usepackage[danish]{babel} % danske overskrifter
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{graphicx}
\usepackage{mathtools}
\usepackage{amsmath}

\begin{document}

\begin{equation}
\begin{aligned}
\frac{d^{2} \left( EI\frac{d^{2}\omega}{dx^{2}} \right)}  {dx^{2}}=p \quad& \Leftrightarrow \\
EI\frac{d^{2}  \left( \frac{d^{2}\omega}{dx^{2}} \right)} {dx^{2}}=p \quad& \Leftrightarrow \\
\frac{d^{4}\omega}{dx^{4}}=\frac{p}{EI}
\end{aligned}
\end{equation}

\end{document}

Without further modification, that'll put the tag vertically in the middle of the series. If you want it only to attach to the last line, you might prefer Stefan's suggestion.